Wed, 08/04/2010 - 13:58
First off, Hello to everyone!
My Name is Brian, and I recently became the owner of a 1977 R100RS, I have never had a BMW nor do I know anything about them… lol
My last bike was a ’07 Suzuki Gsx R600, had to sell due to financial reasons, and miss it.
My father-in-law had this bike in his shed, he had given it to my wife before we met and her late husband had tinkered with it some, what he attempted to do was the “Dual Pluggin” I haven’t been able to find very much info on this, what I have found I don’t know if I like the sounds of it, with Timing, points and all the mods you have to do.
My question is, “is this a good modification or is it bad?” I know it also depends on how it was done, who done, it and if it was done right, that’s what I don’t know I am opening up a can of worms with this bike because I have no clue what he had done to it. I do know that the wiring harness is a mess, it appears that it has caught on fire before. My father-in-law is trying to find the Clymer service manual he had for it, so I can make a new wiring harness.
I did manage to get it started but I think the timing is off, and now it is not firing at all. IMO I think the rings are bad, it smokes a little bit and the right side seems to have more compression than the left, and I hear a lot of “pinging”. I am thinking about getting new rings another set of heads and going back stock with this bike? Thought, Input, on that?
Also I am still trying to find places to get parts, any recommendations would be appreciated.
I want to do this bike in the Café Racer style, I have mechanical experience, just not with BMW, this engine reminds me of a VW engine. I am also a fabricator, welder by trade, so I am able to do pretty much anything I set my mind to.
I will try and post some pictures later.
Greatly appreciate any and all input, or advice!
Thank you
Brian
- 1737 reads
Wed, 08/04/2010 - 15:54
#2
Thank you, for the info
Thank you, for the info Kurt!
I will get some pics posted by tonight.
It doesn't have the original fairings, it had a R90 fairing on it, and the last person done a crummy pain job on it also, it was originally the burnt orange color.
The weird thing is my father in law said that it only had a single rotor on it when he had it and R90 forks, that has been changed since and it has dual rotors. This bike is a real mess... lol
The frame and engine numbers do match though.
Thanks again.
Brian
Wed, 08/04/2010 - 17:45
#3
This is how bad the wiring is
This is how bad the wiring is just rigged on here and spliced together.
Does this red thing on the generator have something to do with the dual plugging? I have not seen anything like this in pictures of stock engines.
Wed, 08/04/2010 - 18:01
#4
I know most of you probably
I know most of you probably like to restore to original, but this is along the style I want to transform this bike into.
http://www.youtube.com/watch?v=qdUi78obJyk
I have seen pics of this bike, but can't seem to find them now, just the video of it.
I think this bike looks sharp!
Wed, 08/04/2010 - 18:24
#5
You've got a tiger by the
You've got a tiger by the tail there...that looks like a small battery in there...it should basically fill the tray. The red thing is a crankshaft-mounted electronic ignition system. The points are below the alternator and are probably not hooked up. Not sure off-hand who makes that ignition system...there's probably something stamped into the unit that would tell you. Looks like it also has a non-stock diode board above, where all the three wires are going to.
That sure is a rat's nest of wires. You'll need to get a good wiring diagram and follow things around. There's one here for the '78s...probably should be mostly the same:
Wed, 08/04/2010 - 18:36
#6
Yes it is a mess....
I'm
Yes it is a mess....
I'm hoping to try and figure things out, may just end up going back all stock and single plugs. At least that way I can go by the service manual, and know what is on it.
Thanks for the link
Sat, 08/28/2010 - 06:31
#7
For the time being why don't
For the time being why don't you just remove the extra plug wires (leave the extra plugs in the head) and get everything sorted out before you sink alot of money into replacing the heads. You have a great start on a great bike! Ya, it's not as fast or handle like your other bike you had, but a fun bike that everyone knows and likes, you'll see.
Mon, 04/25/2011 - 20:35
#8
Brian great choice on the
Brian great choice on the bike grin....
I also have a 77RS, my second one of the same year.....happy to help you out with pictures of what is wired to what if you like.....give a shout
Shiny side up
Pete
Fri, 09/09/2011 - 23:56
#9
I'm back....
Hey guy's! I got lost for a year.... lol
Not really, after looking at part prices a bit back when i posted on here, I decided that this bike was to expensive for me to mess with so I pushed it back and covered with a tarp. bought a 1977 Honda CB750 that I built over about 10months this is it now.
If your iterested you can see my whole build thread here.Honda CB850 build
I still need to get better pictures of it but haven't yet, bored it over to an 850cc and it will scoot..lol
I stumbled upon this site tonight, my other computer crashed that had this saved in my favorites and I have been wracking my brain trying to remember the name of this forum, and now i have found it again..
Anyway after building that bike I have decided to uncover the old BMW now, moved it in the shed the other day and started tearing it down, and dang..... I have never seen so many mix matched bolts, and RTV silicone... The pistons and cylinders are in pretty bad shape, one of the exhaust nuts was JB welded on so no threads left. I'm afraid I opened a can of worms I can't afford to rebuild, but I will, and it will be my winter project. I have been browsing the web for parts and places, seems kind of scarce.
The heads as far as valves, guides, springs, seem to be good, but the bottom plug hole, I'm wanting to weld up and go back stock, and also go back to the points instead of the electronic ing. I have a buddy that done my machining for my Honda, he owns a VW shop and can do pretty much any machine work. When i look at this engine it reminds me of a VW engine..lol So I have been throwing the idea around if it is at all possible to use VW pistons, the skirts could be trimmed down if need be but I don't know what the measurements are from top of the pin to the top of the piston a vw 94mm piston or what the pin size is either. Just thinking out loud here, haven't done any measuring or specs search yet. The gouges in the cylinders are to deep for the .025mm over pistons I think, and plus the cost of BMW pistons is crazy... I haven't seen cylinders for sale either, can you find sleeves and just re-sleeve? a I haven't checked the specs or measurements yet , but sure seems to be alot of play in the rod bearings, and the pin bushing in the rod has a deep gouge in it also. the cam and crank seem to be fine as does the timing chain, I don't know if i'm going to go any deeper than just a top end and fresh gaskets, rod bearings, new bolts. Seems I have my work cut out for me and more so on my wallet.. haha.
Sun, 10/30/2011 - 17:28
#10
price increase
Hate to hear it Brian, the RS would have been worth the time and investment......
However, on the flip side, you increased the worth of mine, by taking yours off the road....
There weren't that many 77's as it was the first year for the radical style change....and if you are fortunate enough to have one without the CFO prefix on the serial number, it's worth even more....
Guess you could always part it out and use the $$ to build and rebuild the Honda...
Cheers
Pietro
Nice bike...the '77 R100RS is probably one of the premier BMWs to have. Great fairing and one of the most powerful BMWs built before they started in on the EPA mods that toned the bike down. Do you have still have the fairing? What color? I'll be nice to see your pictures.
As for dual plugging... It's a nice mod but IMO, not a must. It's greatest claim to fame is to get it to run on lower octane fuel and probably improve starting. It will also help eliminate the pinging since you have two flame fronts to help burn the gas before the piston gets to TDC.
But the timing has to be adjusted. There are two ways. The simplest way is to set the static timing such that the points open very near OT...this is different than the usual timing which is the S-mark or about 6-9 degrees BTDC. The second way is to leave static timing the way it is (at the S-mark) but limit the range of full advance. The reason for all this is that since you have two flame fronts, the cylinder charge burns faster, so you need spark faster.
Tom Cutter wrote a book on dual plugging. It's available here:
http://rubberchickenracinggarage.com/Downloads/TomCutterDualPlugIgnition...
Tom is a BMW trained mechanic and has recently been given the Friend of the Marque honor. That's high praise indeed. You can take anything he says to the bank. Great guy. Be sure and read the disclaimer, however, at the front of this document. He readily admits that things have changed regarding dual plugging.
You would do well to bookmark Snowbum's website at http://bmwmotorcycletech.info/techindex.htm. He also has article on dual plugging at:
http://bmwmotorcycletech.info/dualplugging.htm
Another guy on the other coast that is very good with BMWs and has experimented a lot with dual plugging is Ted Porter. His website is http://www.beemershop.com.
That said, a properly tuned bike does not need dual plugging. My /7, nearly the same as your bike, runs find on premium gas. I do have 100K on the bike and she's in need of a top end, so I get some pinging if the gas is not quite up to snuff or I really get on it. But dual plugging is not the bees knees in all cases.
Tom and Ted are good for parts and tech support. BMW Hucky's is also good for parts. Used parts available here in Texas is Mickey at Airhead Salvage, outside of San Marcos. Website is http://www.airheadsalvage.com.
Dallas/Forth Worth is your closest bet for quick support. Another place that comes to mind is Boxers by Bruce. http://www.boxerbruce.com/. He's a pretty decent guy too.
The smoking could be just due to sitting too long. Doing a compression check or leak down test will let you know what's going on. Getting the bike timed right and using quality gas may eliminate the pinging.
If it were me, I'd try to get all the mechanicals worked out and see how she ran before I made wholesale changes. But you're also looking at all fluids, possibly even bearings in the wheels, tires, battery, etc.
If you want, we can start an oil and tire thread!! Uh, let's not...for now.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2